An accurate physical model of a protein, based on its atomic coordinate data and created by rapid prototyping technology, is an effective new tool to communicate the essential details of a new structure to the biochemists and molecular biologists who are working to understand the role of that protein in human health and disease. 3D Molecular Designs (3DMD) has contributed to the development of this technology by creating software (RP-RasMol) that directly outputs the file format needed by rapid prototyping machines. As more researchers and educators become aware of the availability of these physical models, there is a growing need for new software that will allow these clients to play a more active role in the design of the model. We propose to build a Web-based, goal-oriented Client-Accessible Design Interface for Molecules (CADIMol) that will meet this need. CADI-Mol will employ the open-source software Jmol to display interactive 3D molecular models in any popular browser, and in all common operating systems. Clients will initially choose from four basic model formats, and then refine their design in a series of steps that each provide immediate visual feedback. The design will then be automatically ported to RP-RasMol where it will be converted into a rapid prototyping format and further optimized by 3DMD staff designers. The final optimized design will then be presented back to the client in a Design Review Interface for final approval. We believe that immediate visual feedback, combined with the power of interactive 3D visualization, will ultimately produce a design that accurately represents the client's own mental image of the physical model, but at a fraction of the effort currently required of 3DMD staff designers. The effect of this innovation will be the broader application of rapid prototyping technologies to produce physical models of molecular structures that can be used as both "thinking tools" and "communication tools" by scientists and educators in structure-based research labs. [unreadable] [unreadable]